9 photos of the Chicago River dyed green to celebrate St. Patrick’s Day

Every March since 1962, a local plumbers union has taken to the Chicago River with an armada of boats and dropped gallons and gallons of dye into the water to the celebrate St. Patrick’s Day.

The result is an absolutely stunning (and allegedly environmentally-friendly) transformation of the river into a sea of bright green. Oddly enough, the dye used to change the water from blue to green is actually an orange formula. A mix of boats are used with some responsible for pouring the dye while others trail behind the mix it into the water.

The vibrant green color begins to appear in minutes and can last anywhere from hours to days. Chicago dyed the river on March 11, 2023, a week ahead of St. Patrick’s Day, but you’d never know it wasn’t the actual holiday from the turnout.

It’s a spectacle that has to be seen in person to fully appreciate but these pictures help do it justice.